Getting out and about to measure urban air quality

Traffic is a major source of air pollution in urban areas. Metropolia’s ‘Sniffer’ is one of the advanced tools being used to measure and quantify the amount of exposure people are being subjected to in their daily lives.

Urban air quality is largely shaped by trafficrelated emissions released close to the ground. Recent toxicological and epidemiological studies have confirmed that the particulate and gaseous contents of vehicle exhaust, together with street dust, represent a growing hazard to human health, in addition to the role they play in reducing visibility and acerbating the greenhouse gas problem.

These issues were among those addressed by the FINE Particles – Technology, Environment and Health Technology Programme, which ran between 2002 and 2005, and the mobile laboratory known as the ‘Sniffer’ designed and built by the Metropolia University of Applied Sciences. The latter, which offers a unique technological platform, was employed for vehicle chase measurements and for roadside and other atmospheric aerosol studies, and is now being used in further projects.

The instrumentation in the Sniffer can measure particle number concentrations together with number size distributions, particle mass concentrations, trace gas concentrations, and meteorological and geographical parameters – for use in efforts to improve urban air quality, plan land use, and assess exposure to traffic pollutants near roads.

Two ongoing projects

One of the projects the Sniffer is currently being used in is REAL-EM, involving the Max Planck Institute, DRL, MAN, and the Tampere University of Technology, and focusing on the effect of new exhaust after-treatment, lubricant, and fuel technologies on vehicle emissions under both real-life and laboratory conditions. Particular emphasis is being given to the sulphur content of lubricants and fuel, as well as biofuels. The emissions of cars retrofitted with aftertreatment systems are also being looked at, with an eye to how this technology can be improved to reduce health impact.

Metropolia will be responsible for vehicle chase work, dynamometer measurements of diesel passenger vehicles in its emission laboratory, and modelling issues related to particle formation and growth.

The Sniffer has also been used as part of the ongoing KAPU project to measure springtime street dust in six Finnish cities. These non-exhaust particles are mainly abrasion products originating from the interaction between street surfaces and tyres; their resuspension has a major impact on air quality during the spring in Finland and results in EU limits being exceeded on some occasions.

This is a particular problem in Scandinavia, due to the use of studded tyres and sanding during the winter. Metropolia is working with the University of Stockholm and partners from Germany, as well as the Helsinki Environment Centre and Nordic Envicon, on this project, which includes testing the efficiency of new-generation street cleaning machines and methods.

When measuring street dust emissions, the Sniffer sucks sample air from a conical inlet behind the left rear tyre.